You can use the default queries from pre-built schemas as template, modify them according needs, and store them into your own schemas.
1. Select any of the pre-built schemas, and click one of the queries under it:
2. This will take you to the QUERY tab and load the selected query into the configuration:
3. Now you can remove or add fields, validate (run) the query for 1 day range with good amount of data (this is how Supermetrics for BigQuery extracts data) and store it to your schema.